Underground piping for water, oil and gas has been very difficult to repair, not only because breaks are difficult to locate and must be dug out, but also because organic ground compounds bind themselves to the periphery of the pipe. It is imperative that this foreign material be removed in order to properly repair the break.
Water main piping may be cast iron, ductal iron, asbestos cement, or concrete pipe and usually 4 to 30 inches in diameter, and breaks in these pipes usually occur in a circumferential direction although in some cases they are longitudinal. After the break is located and isolated from the remainder of the system by appropriately closing adjacent shut-off valves, a hole is dug approximately 5 feet wide and 10 feet long to below the depth of the pipe.
Then, gray clay and other foreign material including organic compounds bound to the periphery of the pipe in the area of the break must be removed by scraping and chiseling. After the pipe is smooth in the area of the break, a neoprene liner is wrapped around the pipe sealing the break and a stainless steel repair sleeve, which is essentially a C clamp, is placed over the neoprene liner and sealer and clamped in position sealing the pipe and completing the repair.
Any foreign material remaining on the pipe exterior underneath the sleeve is a source of continued leakage and hence must be removed during the scraping and chiseling procedure.
One prior device to assist in scraping this foreign material from the pipe surface includes a watchband-like strip carrying a plurality of U-shaped channel-like scrapers. The watchband strip includes a plurality of plates interconnected by hinge pins that limit the pivotal movement of each plate to a single direction with respect to adjacent plates.
While this scraper provides improved scraping over the hand chiseling process, it is not possible to provide any twisting motion to the strip because it places an inordinate load on the hinge pins between the plate. Furthermore, the scraper is cumbersome because it cannot be collapsed for storage on the utility truck when not in use. Furthermore, the U-shaped scrapers, because the open end of the U faces the pipe during scraping, are proned to clogging with hard foreign material and, thus, require maintenance, and also the hinges must be lubricated regularly.
It is a primary object of the present invention to provide an improved pipe scraper that eliminates the problems noted above in prior scrapers.